Exhaust tube for down-hole drill



Sept. 8, 1970 c. o. BOOM EXHAUST TUBE FOR DOWN-HOLE DRILL 2 Sheets-Sheet l Filed Sept. 26, 1968 INVENTOR.

4 C/arence 0. 500m A geni C. O. BOOM EXHAUST TUBE FOR DOWN-HOLE DRILL Sept. s, 1970 2 Sheets-5heet 2 Filed Sept. 25, 1968 United States Patent O 3,527,239 EXHAUST TUBE FOR DOWN-HOLE DRILL Clarence 0. Boom, Littleton, Colo., assignor to Gardner- Denver Company, Quincy, Ill., a corporation of Delaware Filed Sept. 26, 1968, Ser. No. 762,803 Int. Cl. E21c 7/.00; E21b l/OO U.S. Cl. 173--67 4 Claims ABSTRACT OF THE DISCLOSURE A combination exhaust, lifting air, and auxiliary holecleansing air tube for a down-hole percussion drill. The tube comprises a centrally positioned tubular element divided into parallel exhaust passages both in communication with the drill hammer driving and lifting air expansion chambers. A partition divides the tube into the parallel exhaust passages and also forms elongated conduits for conducting hammer lifting air, and auxiliary hole-cleansing air.

BACKGROUND OF THE INVENTION A class of fluid operated percussion rock drills known commonly as down-hole drills are usually designed to include a iluid operated piston hammer reciprocally disposed in an elongated cylinder to deliver impact blows directly to a drill bit. Exhaust fluid from the drill percussion motor is usually directed through passages in the bit to provide hole cleansing fluid. Due to the fact that down-hole drills follow the drill bit into the hole being drilled, it is accordingly necessary that the drill proper be of compact design since the drill housing must be of a diameter somewhat less than the diameter of the drill bit. It is also desirable that the diameter of the hammer piston be as great as possible to maximize the piston pressure surface area so that greater impact blows can be delivered to the bit by the pressure fluid acting thereon. These design objectives are difficult to realize and yet provide for suitably sized exhaust passages leading from the percussion motor to the drill bit. It has also been a problem in down-hole drill design to make provision for adequate hammer lifting iluid passages and auxiliary hole cleansing fluid passages.

SUMMARY OF THE INVENTION The present invention provides improved means for supplying hammer lifting fluid, auxiliary hole cleansing fluid, and exhaust fluid passages in a down-hole percussion drill. By providing the centrally located multipassage tubular element herein disclosed extending centrally from the drill motive lluid inlet through a coaxial bore in the drill hammer, and into a receiving bore in the drill bit, adequate fluid passage area is provided for all of the aforementioned functions without greatly reducing drill hammer pressure surface area or increasing the drill housing diameter.

The present invention also provides a centrally positioned tube having an auxiliary iluid conduit for conducting pressure fluid directly to the drill bit for improved hole cleansing during deep-hole drilling when exhaust fluid alone is insuiiicient to provide adequate hole cleansing. The auxiliary hole cleansing liuid conduit ad-l vantageously bypasses the distributing valve and the percussion motor and thereby does not adversely affect the operation of the drill. The invention also provides for means to prevent hammer reciprocation when the drill bit is olf the bottom of the hole and concurrently provide for all motive fluid to the drill to be directed to the bit for hole cleansing.

An advantage of the present invention lies in the pro- "ice vision of a multipassage tubular element of unique construction which performs numerous functions in a downhole drill while occupying a minimum of space in the drill proper and being easily removable from the drill.

These and other advantages of the invention will be appreciated upon reading the description of the preferred embodiment.

BRIEF DESCRIPTION O'F THE DRAWING FIG. 1 is a longitudinal section view of a portion of a down-hole drill employing the novel exhaust tube herein disclosed.

FIG. 1a is a continuation of FIG. l from the line a-a illustrating the lower portion of the down-hole drill.

FIG. 2 is an exterior View of the exhaust tube for the down-hole drill shown in FIGS. 1 and la.

FIG. 3 is a transverse section taken along the line 3--3 of FIG. 2.

FIG. 4 is a transverse section taken along the line 4-4 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 and FIG. la, a typical down-hole percussion rock drill is illustrated in longitudinal section and generally designated by the numeral 10. The drill 10 is adapted to be suspended from the end of a string of hollow drill pipe 12 in the conventional manner by a threaded connection 14 in the drill backhead 16. The drill 10 basically comprises the backhead 16 threadedly connected to an elongated cylindrical housing 18 having a bore 20 forming with a movable piston hammer 22 a fluid operated percussion motor. The piston hammer 22 includes opposed pressure surfaces 21 and 23 and divides the bore 20 into expansible chambers 24 and 26 which permit the expansion of pressure iluid for driving and lifting the piston hammer 22, respectively. The expansion chamber 26 is closed at its lower end by a chuck member 28 threadedly secured to the drill motor housing 18 and slidably retaining a percussion drill bit 30. The bit 30 is of the integral shank type having an elongated shank portion 32 axially slidably retained in the chuck 28 by means of the lugs 34 and the retainer 36. As can be seen in FIG. 1a the shank portion 32 is adapted to receive percussion blows directly from the piston hammer 22.

The backhead 16 includes a passage 38 in fluid ow communication with the hollow drill pipe 12 and opening into an area 40 from which a plurality of conduits 42 communicate with the space 44. A check valve 46 is suitably biased in the position shown by a spring 48 retained in a housing 50. Located in a bore 52 in the upper portion of the drill motor housing 18 a platelike member 54 abuts the lower end of the backhead 16 and retains a fluid distributing valve chest 56. The plate 54 includes a series of openings 58 in communication with the space 44 and plural conduits 60 located near the periphery of the valve chest 56. The plate 54 also includes the openings 62 formed at an angle with respect to the longitudinal axis of the drill 10 and opening into the recessed area 64.

The distributing valve chest 56. comprises a housing for an axially shiftable valve element 66 having opposed pressure surfaces 68 and 70. The valve 66 is of a type well `known to those familiar with the art of fluid operated percussion tools and is operable in response to pressure forces acting alternately on the pressure surfaces 68 and 70 to shift to valve pressure yfluid to the expansion chambers 24 and 26, respectively.

A multipassage fluid conducting tube, generally designated by the numeral 72, is retained at the valve chest 56 by a flanged head 74. The tube 72 is substantially coaxial with the longitudinal axis of the drill 10 and extends through the valve chest 56, the piston hammer 22,

and into a central bore 76 in the shank portion 32 of the bit 30. The tube 72 includes an outer cylndrical tube 78 having a bore 80 divided into parallel circular segment shaped passages 81, FIGS. 3 and 4, by a central partition 82 disposed in and extending the length of the tube 78 and having a portion 83, FIG. 2, closing the bore 80 at the flanged head end. The passages 81 are of substantially equal cross sectional area and serve to conduct exhaust pressure uid from the expansion chambers 24 and 26 by means of the longitudinally spaced double exhaust ports 84 and 86, respectively. The exhaust passages 81 open into the bore 76 in the bit 30` from where passages 88 and 90 lead to the exterior of the drill 10.

The central partition 82 includes a longitudinal conduit 92 in communication fwith the area 64 at the head end of the tube 72 and opening into the bore 76 in the bit 30 through the plug 94 having an oriiice 96 therethrough. A parallel conduit 98 extending longitudinally through the partition 82 is in fluid-ow communication with the annular area 100 surrounding the valve element 6'6- by means of the opening 102, and at the lower or bit end of the tube 72 the conduit 98 opens through the aperture 110 into an area 104 formed by an enlarged portion 106 of the bore 76 and a recessed portion 108 of the tube 7.8. As can be seen in FIG. la the area 104 forms a flow passage for conducting pressure Huid to the expansion chamber 26 when the bit 30 is in the position shown. A third opening 112 from the conduit 98 (FIG. 1) is operable to communicate pressure fluid to the expansion chamber 24 in response to the piston hammer 22 being in a certain position to be described below.

The functional aspects of the multipassage tube 72 can best be understood by an explanation of the operation of the drill As previously mentioned, the drill 10 is of the down-hole type whereby it is attached to the end of the drill pipe 12 which is rotated by suitable means, not shown, and which supplies pressure uid such as compressed air from a suitable source to operate the drill percussive motor and provide a cleansing medium for evacuating drill cuttings from the drill hole. In operation, the weight of drill 10 will cause the bit 30 to assume the position shown in FIG. la when the latter is in contact with the bottom of a drill hole. Pressure ilu-id from the drill pipe 12 will ow through the passage 38 in the backhead 16 past the check valve 46, which will be pressure biased open, into the area 40, through the plural conduits 42, into the space 44, and through the passages 58 and 60 to the valve element 66. With the valve element 66 in the position shown in FIG. 1 fluid will -flow past the perimeter of the valve and via the annular area 114 into the expansion chamber 24 to drive the piston hammer 22 downward to strike the bit 30 as shown by the position of the hammer in FIGS. l and la. As the hammer 22 travels downward to the position shown, the exhaust ports 86 for the expansion chamber 26 become closed by the close fitting bore 116 of the hammer 22 thereby resulting in a pressure increase in the expansion chamber 26 due to uid trapped therein. This pressure increase is transmitted via the area 104 and the conduit 98 into the annular area 100 to act on the pressure surface 70 of the valve 66 causing it to shift downward thereby cutting off the communication of pressure fluid to the expansion chamber 24. Also as the hammer 22 travels downward to the position shown, the exhaust ports 84 into the expansion chamber 24 are uncovered permitting exhausting of pressure fluid through i the parallel passages 81 (FIGS. 3 and 4) into the bore 76 and through the passages 88 and 90 to aid in evacuating drill cuttings from the drill hole. With the valve ele ment 66 shifted as described above pressure fluid from the passages 60 will flow into the annular area 100 and down through the conduit 98, the area 104 and between the coacting surfaces of the hammer and bit into the expansion chamber 26 to lift the hammer 22 upward uncovering the exhaust ports `86 and closing off the exhaust ports 84 permitting exhausting of fluid from the expansion chamber 26y through the passages 81, and causing a pressure increase in the expansion chamber 24. The pressure rise in the chamber 24 will accordingly act on the surface 68 of the valve 66 causing the same to shift to the position shown in FIG. 1 whereby pressure iluid will again be communicated to the chamber 24 for providing power to the hammer 22 to strike the bit 30. The aforedescribed cycle is, of course, repeated rapidly in actual operation of the drill 10.

Concurrently with operation of the drill 10, a continuous supply of hole cleansing fluid is supplied to the bore 76 of the bit 30 by way of the passages 62 in the plate 54 into the area 64 and through the elongated conduit 92 and the orifice 96. The orifice 96 is suitably sized to limit the amount of iluid bypassed from the drill percussion motor and the plug 94 is slidably retained in the conduit 92 and thereby is easily removed and replaced with a larger or smaller orice depending on hole cleansing require-ments. For example, as the depth of the drill hole increases greater amounts of high pressure fluid are required to be bypassed around the percussion motor to provide adequate fluid energy for removing drill cuttings from the hole, thus necessitating a large orice. However, in shallow holes or when rst starting the drill hole little or no auxiliary hole cleansing fluid is usually required whereby a small oriiice or a solid plug may be inserted in the conduit 92 and hence exhaust fluid alone substantially meets hole cleaning requirements. Removal of the plug 94 or the entire tube 72 is accomplished by unscrewing the backhead 16 from the housing 18 and lifting the plate 54 out of the bore 52.

'Means are also provided for maximum hole cleansing requirements using all of the fluid supplied to the drill 10 and to prevent operation of the percussion motor when the bit 30 is out of contact with the bottom of the hole being drilled. When the drill 10 is raised oif the bottom of the hole, the bit 30 will drop down until the lugs 34 contact the retainer 36. This position of the bit places the close tting portion 120 of the bore 76 sealingly over the opening 110 into the lifting uid supply conduit 98. Concurrently, the hammer 22 will drop down along with the bit 30 thereby placing the conduit 98 in communication with the expansion chamber 24 by means of the opening 112. The area now |being vented to chamber 24 will cause the valve 66 to remain in the position of FIG. 1 l

to supply pressure fluid through the area 114 to the chamlber 24 and through the exhaust ports y84 and parallel passages y81 to the bore 76 in the bit 30 along with, of course, fluid being bypassed continuously through the auX- iliary conduit 92. Hammer reciprocation is thereby prevented and .all fluid supplied to the drill 10 is used for hole cleansing medium under higher pressure than when the combination of low pressure exhaust fluid and oriced hole cleansing uid is used during normal operation. As can be readily appreciated from the foregoing description and the accompanying illustration, the tube 72 serves a number of functions including providing ample sized exhaust passages, a bypass auxiliary hole cleansing conduit, a lifting uid conduit, means for providing maximum hole cleansing fluid at high pressure, and preventing unwanted hammer reciprocation when the drill 10 is out of contact with the work. All of these functions are provided with a compactly designed tube adapted for ease of assembly and removal from the drill.

In a preferred method of manufacture of the tube 72, the outer cylindrical tube portion 78 and the partition 82 are separately fabricated of steel. The partition '82 is made to have a close sliding or light press t in the bore 80. After assembly, the components are welded at suitably accessible locations and the head end of conduit 98 is plugged as shown in FIG. 1. Separate fabrication of the tube 78 and the partition -82 provide for a tube having maximum ow area for exhaust uid through the circular segment passages 81 thereby formed, as well as providing for conduits 92 and 98, and yielding a structure satisfying performance requirements at low manufacturing cost` What is claimed is:

1. Multipassage fluid conducting means for a down-hole drill, said means comprising an elongated substantially cylindrical tube having a hollow bore therethrough, a partition disposed in said bore and having a portion closing one end of said bore, said partition extending substantially the length of said tube and dividing said tube into parallel passage means, said passage means opening to the exterior of said tube at the end of said bore opposite said closed end, said partition including first conduit means extending longitudinally through said partition and opening axially to both ends of said tube and second conduit means extending longitudially Within said partition and opening to the exterior of said tube through a plurality of spaced radial openings, and longituidnally spaced port means in said tube opening from the exterior of said tube into said parallel passage means.

2. The invention set forth in claim 1 wherein:

said partition is centrally positioned in said bore of said tu'be whereby said parallel passage means are formed of substantially equal cross sectional areas.

3. Fluid conducting means for a pressure fluid operated percussion drill, said drill including:

a pressure tiuid percussion motor having a piston hammer reciprocably disposed in a cylinder and forming therewith opposed expansion chambers for driving and lifting said hammer respectively;

pressure Huid inlet means and fluid distributing means in communication with said inlet and operable to distribute pressure uid alternately to said opposed expansion chambers;

blow receiving means disposed in one end of said percussion motor including a bore in communication with the exterior of said drill, and said Huid conducting means comprising:

an elongated substantially cylindrical walled hollow tube located in said motor cylinder and extending from said fluid inlet means to said bore in said blow receiving means;

a longitudinal partition disposed within said hollow tube forming a pair of elongated parallel passages between said tube wall and said partition, said tube including exhaust port means opening into said parallel passages from said opposed expansion chambers;

first conduit means extending longitudinally through said partition from said uid inlet means to said bore in said blow receiving means for conducting pressure fluid directly to said bore in said blow receiving means; and,

second conduit means extending longitudinally within said partition for conducting pressure uid from said fluid distributing means to said hammer lifting expansion chamber.

4. The invention set forth in claim 3 wherein:

said first conduit means includes variable orifice means for limiting the amount of pressure fluid conducted by said rst conduit means to said bore in said blow receiving means.

References Cited UNITED STATES PATENTS FOREIGN PATENTS 8/ 1964 England.

JAMES A. LEPPINK, Primary Examiner 

